Background: The CD38 transmembrane glycoprotein is an ADP-ribosyl cyclase that moonlights
as a receptor in cells of the immune system. Both functions are independently implicated in
numerous areas related to human health. This study originated from an inherent interest in
studying CD38 in the cynomolgus monkey (Macaca fascicularis), a species closely related to humans
that also represents a cogent animal model for the biomedical analysis of CD38.
Results: A cDNA was isolated from cynomolgus macaque peripheral blood leukocytes and is
predicted to encode a type II membrane protein of 301 amino acids with 92% identity to human
CD38. Both RT-PCR-mediated cDNA cloning and genomic DNA PCR surveying were possible
with heterologous human CD38 primers, demonstrating the striking conservation of CD38 in these
primates. Transfection of the cDNA coincided with: (i) surface expression of cynomolgus macaque
CD38 by immunofluorescence; (ii) detection of ~42 and 84 kDa proteins by Western blot and (iii)
the appearance of ecto-enzymatic activity. Monoclonal antibodies were raised against the
cynomolgus CD38 ectodomain and were either species-specific or cross-reactive with human
CD38, in which case they were directed against a common disulfide-requiring conformational
epitope that was mapped to the C-terminal disulfide loop.
Conclusion: This multi-faceted characterization of CD38 from cynomolgus macaque
demonstrates its high genetic and biochemical similarities with human CD38 while the
immunological comparison adds new insights into the dominant epitopes of the primate CD38
ectodomain. These results open new prospects for the biomedical and pharmacological
investigations of this receptor-enzyme.

Background: The CD38 transmembrane glycoprotein is an ADP-ribosyl cyclase that moonlights
as a receptor in cells of the immune system. Both functions are independently implicated in
numerous areas related to human health. This study originated from an inherent interest in
studying CD38 in the cynomolgus monkey (Macaca fascicularis), a species closely related to humans
that also represents a cogent animal model for the biomedical analysis of CD38.
Results: A cDNA was isolated from cynomolgus macaque peripheral blood leukocytes and is
predicted to encode a type II membrane protein of 301 amino acids with 92% identity to human
CD38. Both RT-PCR-mediated cDNA cloning and genomic DNA PCR surveying were possible
with heterologous human CD38 primers, demonstrating the striking conservation of CD38 in these
primates. Transfection of the cDNA coincided with: (i) surface expression of cynomolgus macaque
CD38 by immunofluorescence; (ii) detection of ~42 and 84 kDa proteins by Western blot and (iii)
the appearance of ecto-enzymatic activity. Monoclonal antibodies were raised against the
cynomolgus CD38 ectodomain and were either species-specific or cross-reactive with human
CD38, in which case they were directed against a common disulfide-requiring conformational
epitope that was mapped to the C-terminal disulfide loop.
Conclusion: This multi-faceted characterization of CD38 from cynomolgus macaque
demonstrates its high genetic and biochemical similarities with human CD38 while the
immunological comparison adds new insights into the dominant epitopes of the primate CD38
ectodomain. These results open new prospects for the biomedical and pharmacological
investigations of this receptor-enzyme.